Method and apparatus for drying



Aug. 16', 1938. V F. s. sum-1 V 2,127,474

mETaon' AND APPARATUS FOR DRYING Filed Aug. 2, 1935 2 Sheets-Sheet 1DRYING CHAMBER PUHIFIER mvENTbR fianmm 5. 5mm

ATTORNEYS Aug. 16,1938. F. 5. SMITH METHOD AND APPARATUS FOR DRYING.Filed Aug. 2. 1935 2 Sheets-Sheet 2 FROM DRYING CHAMBER 6O BNVENTORFROM FUR! PIER 69 ATTORNEYS ratus for drying.

r uses.

Patented Aug. 16, I938 METHOD AND APPARATUS FOR. DRYING Franklin S.Smith, New Haven, Conn.

Application August 2, 1935, Serial No. 34,313

JAN 7 194i EISSUE 9 Claims. (Cl. 34-24 This invention relates to amethod and appa- One of the objects of this invention is to provide anapparatus for vacuum drying which is simple and practical inconstruction and efficient and reliable in operation. Another object-isto provide apparatus of the above nature which can be inexpensivelymanufactured and readily assembled.. Another object is to provide amethod of the above nature which can be carried out with maximumemciency in an inexpensive and simple manner. Another object is toprovide a method of the above nature which is thoroughly" dependable andamenable to a great variety oi Other objects will be in part apparentand in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements,

arrangements of parts, and in the several steps and relation and orderof each of the same to one or more of the others, all as will beillustratively described herein, and the scope of the applica-- tion ofwhich will be indicated in the following claims.

In the accompanying drawings in which is shown a preferred embodiment ofthe mechanical features of my invention,

Figure 1 is a diagrammatic view of the several elements of my dryingapparatus;

Figure 2 is a vertical section of the vacuum pump and oil reservoirshown in Figure l; and

Figure 3 is a diagrammatic vertical section of a part of the purifiershown in Figure 1.

Similar reference characters refer to similar parts throughout theseveral views of the drawings.

As conducive to a clearer understanding of certain features'oi thisinvention, it may first be noted that vacuum drying systems depend inpart for efilcient operation upon the lubricating and sealing propertiesof the, oil used in the evacuating device in the system. Accordingly itis primarily mportant that such oil be kept in as pure and unadulteratedcondition as possible. Vacuum drying systems are notorious destroyersand wasters of oil mainly because the oil reconditioner incorporatedtherein is. in many instances, incapable of fulfilling its assignedduty. If these systems be made to utilize some type of settling tankwherein the adulterated oil runs through a filter to separate theforeign solid particles from the oil and water and Permit the wvater tosettle in the bottom of the tank, to be subsequently drained, theresults are unsatis-- factory. While some of the impurities would beseparated in this manner, a large portion of them would still remain inthe oil and be consequently reintroduced into the evacuator. As theseimpurities are constantly flowing into the evacuator with the oil, theyare constantly being dispersed into the oil due to agitation by theevacuator. Aslthe impurities consist of moisture and foreign particles,all the elements are present which upon working will causeemulsiflcation of the oil and the moisture. Accordingly the evacuatorfunctions also as a colloidal mill or homogenizer instead of functioningsolely as a vacuum pump and the oil is impaired as a lubricating andsealing medium. As a settling tank or the like will not separate anemulsion, it would soon become necessary to drain oil the emulsified oiland introduce new and pure oil. Inasmuch as a large quantity of oil isused, this constant changing would not only entail considerable expenseand interrupted operation, but also inconvenience and a problem of wastedisposal. Furthermore, the emulsifying action is considerably expediteddue to the relatively high temperature of the impurities and moisturedrawn into the evacuator from the drying chamber. The heat tends toreduce the viscosity oi the oil, thus rendering it less effective as asealing medium and more amenable to emulsiiication. One of the dominantobjects of this invention is to provide a method and apparatus tor avacuum drying system wherein the above-noted conditions as well as manyothers are practically and ecientiy rectifled.

With reference to Figure i, there is generally indicated at it a dryingchber or the like which is preferably capable oi maintaining a. vacuumand in which may be deposited a mass oi material ti for drying. Chber tiis provided with an opening or port the which receives a pipe M which issuitably connected with a condenser generally indlcated at M and extendstherethrough to connect with a pipe 62a leadmg from the condenser. Apipe dt communicates with the interior of condenser it and introducescooling water therein from any convenient source it to surround pipe 62and cool vapors passing therethrough. Another pipe M connects condenserlit with a suitable waste drain 13 to provide an exhaust channel for thecooling water introduced into the condenser. Thus cool water completelysurrounds and circulates about pipe B2 to reducd' the temperature ofmoisture, gases,

foreign particles and the like withdrawn from chamber til. Y

Pipe 82 2 leads into a vacuum pump generally indicated at 6i. Pump 63,the construction and operation of which will be more fully describedhereinafter, withdraws moisture, gases and foreign particles frommaterial M and deposits them into a sump 84 or the like. Largequantities of. oil used in pump 63 for lubricating and sealing violentagitation of the moving parts of the pump, it is desirable to remove themixture and separate it into its component parts as rapidly as possiblein order to avoid emulsiflcation of the oil and its consequentimpairment as a lubricating and sealing medium. To this end preferably Iprovide a pipe 65 which connects sump 64 with a suitable pump 66belt-driven by a motor I6. Pump 66 sucks the mixture from sump 64through pipe 66 and forces it through a pipe i overflow pipe I6 connectschannel I4. with sump 64 to provide a by-pass for surplus oil in excessof the quantity which reservoir 16a and pump 63 can accommodate.Preferably purifier 69 likewise has an overflow pipe 46 connected tosump 64 to accommodate excess mixture which would otherwise overt/ax thecapacity of the purifier.

Preferably pump 63 is provided with a cooling jacket, illustrativelyshown as a jacket 'IIa, which connects at one end with a pipe 11connected to water source BI and at the other end with a pipe I6connected to drain I3. Accordingly cooling water from source 6lflowsthrough pipe II, water jacket Ila, and pipe I6 to empty into waste drainI3. Thus the heat engendered in pump 63 by friction of moving parts,high pressures and the heat of the foreign particles and moisture israpidly and efliciently dissipated, the purposes and advantages of whichwill be more fully indicated hereinafter.

It may now be seen that the construction is unitary in character andthat the several elements, namely the drier, the condenser, the vacuumpump, the oil pump and the purifier, are so combined as to produce ahighly meritorious result due to their coaction, all as will be morespecifically pointed out hereinafter.

Referring now to Figure 2 of the drawings, vacuum pump 63 comprises abase 5 which supports an outer casing or water jacket 6 which, with aninner wall or casing I, encloses a space 6 through which cooling watermay circulate. Wall 1 also comprises a cylinder wall which encloses acylinder space 9 in which a drive shaft I0 supports an eccentric or campart II. Shaft l6 may be suitably journaled in the ends (not shown) ofthe pump body and is driven in any convenient manner as for example by abelt connected to motor 19 (Figure 1).

Cam ll (Figure 2) has slidably mounted there-' about a piston generallyindicated at l2 having a cylinderical body portion I2a which is of suchasize as to be in tangential contact with the inner surface of easing I.A slide arm IZb is joined to portion I 2a of piston 12 and reciprocatesin a slide pin I3 rotatably mounted in a portion Ia. of easing I. Thusas drive shaft l0 revolves, as indicated by the arrow in Figure 2, camll being driven thereby through a key Ila imparts a rotary motion topiston i2 tangentially about the inside of wall I of cylinder 9. Slidearm I2b reciprocates through slide pin 13 and also rocks back and forthcausing pin l3 to rotate alternately in opposite directions.

Slide arm l2b has a bore l2c connecting with a port IZd formed in theslide arm. As arm l2b operates, it moves upwardly into a chamber I4formed in pump 63 by the upper part of easing I and any substanceflowing through pipe 62a (Figure 1), which communicates with chamber I4by a port I 4a (Figure 2) is admitted into cylinder 9 when arm I2breaches the bottom of its travel permitting port I2d to communicate withthe upper part of cylinder 9.

As piston l2 pursues its tangential travel around the inner surface ofcasing 'I, a vacuum is created behind the piston which draws in air,moisture, and foreign particles from pipe 62a. through hollow portioniZc and port I2d when port IZd passes the bottom of pin 13. Thusmoisture, gases, and foreign particles are sucked out of chamber 60(Figure 1) into pump 63 by way of pipe 62, condenser coil 83, pipe 62a,port Ma (Figure 2), chamber l4, hollow portion I20 and port l2d.

Just before piston I2 attains its highest position, port 12d in arm l2bis completely closed by pin l3, thus forming an efficient mechanicallyoperated suction valve.

The moisture, gases, and foreign particles thus drawn into cylinder 9are expelled through a spring-biased-discharge valve generally indicatedat 15. Valve l5 comprises a port [6 formed in casing I and communicatingwith cylinder 9, a valve seat II, a guide rod I9, a valve spring I8disposed about guide rod" I9 and biasing seat I'I toward a closedposition, and chamber 20 in which the guide rod and spring are disposed.A suitable housing or casing 2| receives the outer end of guide rod i9and provides an abutment 22 against which spring I8 bears in forcing thevalve seat toward its closed position. A suitable channel 2lacommunicates with chamber 20 and is connected to pipe 46 (Figure 1)leading to sump 64. The pressure created in cylinder 9 by the tangentialmovement of piston I2 therein forces valve block II from its seatagainst the action of spring Ill to permit discharge of moisture, gases,foreign particles, and oil from cylinder 9 through port l6, chamber 20,channel 2la, and pipe 46 (Figure 1) into sump 64.

In order to insure eflicient operation 'of pump 63, cooling water iscirculated through water jacket 8, the water being introduced through aninlet 8a connected with pipe 11 from source 8| and escaping through anoutlet 8b connected with pipe I8 leading'to waste drain I3. Reservoir15a is preferably located between purifier 69 and pump 63. Pipe I5(Figure 1) connects the reservoir to channel I4 leading from thepurifier and a pipe 15b (Figure 2) forms an outlet from the reservoir.

Connected to pipe 15b I provide a pipe and a pipe 15d. Pipe I5c connectswith suitable ports (not shown) formed in both ends of pump 63 toprovide oil lines for lubricating and sealing oil for pin l3 and hollowarm l2b. In a substantially similar manner, pipe 15d provides adequateoil for lubricating drive shaft I0 and cam II and for both lubricatingand sealing the bearing surfaces of piston l2 and cylinder wall I. Inthis manner an ample supply of oil is-delivered to both ends of the pumpand the risk of the pump running dry is obviated.

Thus it will be clear that I have provided a suitable pump capable ofefficient operation even when subjected to repeated charges of slugs ormoisture, uncondensed gases and foreign par-' ticles.

During the operation of the pump, the lubricating and sealing oil, usedtherein, comes into continuous contact and is mixed with the liquids,

.gases and foreign particles sucked out .of the If no more than the oiland thus be lost. This would result in a decrease of vacuumpumpefiiciency as the pump has large areas continually in need oflubrication and sealing during the motion of the several moving parts.As the piston in the pump revolves at a high number of revolutions perminute, the oil and impurities are subjected to such great turbulenceand working that the resultant mixture is a sludge which will notreadily separate into its component parts by settling. It follows that awalls of the pump or any other contacting sur faces therein. It is,ofcourse. impossible to settle out the oil in this event. asthe'emulsion is stable and the oil is, therefore. useless for sealing orlubricating purposes In order to prevent the deterioration of the oil byemulsification, the oil should. be separated j from the impuritiesimmediately after leaving the pump and before a sludge can be formed. Inorder to carry out such separation or purification, I provide thecentrifugal purifier 69 (Figures 1 and 3).

A portion of purifier 69 is diagrammatically illustrated in Figure 3wherein pipe 68, leading from pump 66 and sump 64 (Figure 1.). emptiesinto a reservoir .30 or the like suitably mounted in the top of thepurifier. A pipe 3| connects with reservoir 30 and empties-into achamber 32 formed within a suitable separator bowl 35 rotatably mountedon a drive shaft 36. Shaft 36 may be driven through any suitablemechanism such as a countershaft and pulley, generally indicated -at It,by motor 719 and belts 70a and 10b (Figure l).

Suitably disposed within bowl as (Figure 3) 1 preferably provideanelement generally indicated at 33 comprising a substantially tubularportion 33a and a frusto-conical part 330. Thus. when properlypositioned in bowl 35, element 33 forms chamber32 and with bottom ofbowl 35 forms a passage 34.

Another element generally indicated at'3l is likewise disposed immovablywithin bowl 35 and is superimposed about portion 33a of element 33, thusforming a passage 38 with the top of bowl 3% and also a chamber 39 withthe top of part 331) of element 33. Element 3lalso forms a passage towith tubular portion 33a, and portion 330, forms still another passageill with pipe Thus it will be seen that there is provided four passages,namely, inlet passage 34 and the three outlet passages38, 40, and 4|,the purpose and operation of which will be described hereinafter.

Suitably arranged above bowl 35, I provide a series of chambers,preferably three in number and generally indicated at 42, 43 and 44.Chamber 42 connects passage 4| and thus to chamber 32; chamber 42 alsoconnects pipe 46 which leads to sump 64 (Figure 1) to accommodatesurplus sludge. Chamber 43 connects passage 40 and chamber 39 with pipe14 which leads to oil reservoir 15a (Figure 1). Chamber 44 connectspassage 38 with pipe'TZ which leads to waste drain 13 (Figure 1).

In operation the adulterated oil is pumped from sump 64 by pump 66 intoreservoir from which it fiows'through pipe 3| into chamber 32, thencethrough passage 34 into the separator bowl chamber 39. As the separatorvbowl is revolving at a high rate of speed, any substances introducedtherein will be subjected'to the centrifugal force induced by the bowlsrotation. As the mixture in chamber 39 consists of several substanceshaving different specific gravities, the heavier substances are forced.toward the periphery of the bowl to the disadvantage of the lightersubstances whch-are displaced from the outer pertions of the bowl andhence forced toward the center thereof. Thus the foreign particles,being the heaviest components of the mixture, are

. forced against the outer wall 35a of bowl 35 where they form into asticky mud and are removed from the mixture accordingly. The water inthe moisture, having the next highest specific gravity is forced intoportion 39a of chamber 39. The pure oil, having the lowest specificgravity of any of the components of the mixture, thus accumulates in theinner portion of chamber 39 in a substantially unadulterated condition.

As more mixture flows into the bowl. the water in portion 39a. isdisplaced and flows through passage 38 into chamber 44 and from there towaste drain 13 by way of pipe 12. The pure oil in chamber 39 is likewisedisplaced and flows through passage 40 into chamber 43 from which itflows into reservoir. 15a thr'ough pipe 14. If more mixture isintroducedinto the purifier than can be accommodated thereby. anoverflow into sump 64 is provided by way of chamber 32, passage 4|,chamber 42 and pipe 46.

As the mud forming on wall 35a would eventually clogpassage 38 andgenerally impede the operation of the purfier. bowl 35 is so construc edthat vit-can be readily removed for cleaning. In order to clean the bowlit is, of course, necessary to stop the purifier but. in order that theoperation of vacuum pump 53 be uninterrupted, reservolr 75a is ofsufilcient capacity to store enough pure oil-for the needs of the vacuumpump during the cleans ng periods. Sump 64 is likew se ofsufiicientcapacity to receive the m xture durin such periods as Dump 66is shut down when the bowl s being. cleaned. Thus it is not necessary toin errupt the operation of the drying system w le the purifier is beingcleaned.

While the many advantages of my vacuum drier are particularly welladapted to drying paper. for example. such as is used in the manufactureof pcrm ttnrs, its advantages may be equally well utilized in otherfields.

Accordingly it will be seen that I have provided a vacuum drying systemand method of drying wherein the lubricating and sealing oil is main--tained in a pure and undiluted state with the result that the loss ofoil through emulsiflcation is reduced to a minimum, and wherein theseveral objects referred to hereinabove as well as many others areefficiently and successfully achieved.

As many possible embodiments may be made of the above invention, and asmany possible changes may be made in the method hereinabove set forth,all without departing from the scope of the invention, it is to beunderstood that all matter contained herein or shown in the severalviews of the drawings is to be interpreted as illustrative and not in alimiting sense.

I claim:

1. The herein described art which includes the steps of continuouslywithdrawing moisture and particles from a material to be dried, forcingthe moisture and particles-into an oil sealed space wherein the oilmoisture and particles are mixed into a sludge, immediately separatingthe sludge into its component parts, immediately returning the oil tosaid oil sealed space, and discharging the moisture and particles.

2. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off solids, moisture andgases during the drying process, of evacuating means utilizing a sealinglubricant, means connected to said evacuating means for supplyingsealing lubricant to said evacuating means, said evacuating means beingconstructed so that the solids and liquids taken therein are mixed withsaid lubricant to form a sludge, separating means adapted to separatethe lubricant from the solids and liquids, means for conveying saidsludge from said evacuating means to said separating means, and meansfor returning said lubricant from said separating means to said secondmentioned means.

3. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off foreign matter in theform of solids, moisture and gases during the drying process, of acondenser connected to said drying chamber for reducing the foreignmatter to solids and moisture, evacuating means utilizing a sealinglubricant, means connecting the outlet of said condenser to the inlet.of said evacuating means, means connected to said evacuating means forsupplying sealing lubricant to said evacuating means, said evacuatingmeans being constructed so that the solids and liquids coming in fromthe intake side thereof are mixed with said lubricant to form a sludge,separating means adapted to separate the lubricant from the solids andliquids, means for conveying said sludge from said evacuating means tosaid separating means, and means for returning said lubricant from saidseparating means to said third mentioned means.

4. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off solids, moisture andgases during the drying process, of a rotary pump 4 utilizing a sealinglubricant, means connected to said pump for supplying sealing lubricantthereto, said pump being constructed so that the sealing lubricant runsthrough the interior thereof and mixes with the solids and liquids drawntherein to form a sludge, separating means adaptedto separate thelubricant from the solids and liquids,

means for conveying said sludge from said pump to said separating means,and means for returning said lubricant from said separating means tosaid first mentioned means.

5. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off solids, moisture andgases during the drying process, of evacuating means utilizing a sealinglubricant, means connected to said evacuating means for supplyingsealing lubricant to said evacuating means, said evacuating means beingconstructed so that the solids and liquids taken therein are mixed withsaid lubricant to form a sludge, a centrifugal separator, means forconveying said sludge from said evacuating means to said separator, andmeans for returning said lubricant from said separator to said secondmentioned means.

6. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off solids, moisture andgases during the drying process, of a rotary pump utilizing asealing-lubricant, means connected to said pump for supplying sealinglubricant thereto, said pump being constructed so that the sealinglubricant runs through the interior thereof and mixes with the solidsand liquids drawn therein to form a sludge, a centrifugal separator,means for conveying said sludge from said chamber to said separator, andmeans for returning said lubricant from said separator to said firstmentioned means.

"7. The combination with apparatus having a vacuous drying chamber formaterial characterized by a tendency to give off solids, moisture andgases during the drying process, of evacuating means utilizing a sealinglubricant, a storage tank connected to said evacuating means forsupplying sealing lubricant to said evacuating means, said evacuatingmeans being constructed so that the solids and liquids taken therein aremixed with said lubricant to form a sludge, separating means adapted toseparate the lubricant from the solids and liquids, means for conveyingsaid sludge from said evacuating means to said separating means, andmeans-for returning said lubricant from said separating means to saidstorage tank.

8. The herein described art, which includes the steps of evacuating aspace to remove vapors and solid particles from material disposed in thespace, condensing the vapors, transferring the condensate and solidparticles to a chamber sealed by oil so that the condensate and solidparticles are mixed with the oil, removing the resultant mixture,immediately centrifuging the mixture to separate the condensate andsolid particles from the oil before any substantial emulsion of theoil'occurs, and returning the oil to said oil-sealed space.

9. The herein described art, which includes the steps of removing waterand other foreign matter from a material to be dried, transferring thewater and foreign matter to a chamber sealed by oil so that the waterand foreign matter are mixed with the oil, removing the resultantmixture from said oil-sealed chamber, immediately centrifuging themixture to separate the water and foreign matter from the oil before anysubstantial emulsion of the oil occurs, and returning the oil to saidoil-sealed chamber.

FRANKLIN S. SMITH.

n scLA'iME'R 2,]l27,474&.-Fmnklin S. Smith, New Haven, Conn. Mmmcm mmArmmwus FOR DRYING. Patent dated August 16, 193-8. Diselaimer-filediipril 13, 1940, by the assignee, F. J. Stokes Machine Company;

Hereby disclaims the subject matter of each of claims 1, 2, 4, 5, 6-,Hand. 9 of mid Letters Patent.

flame May M 1940.]

